linux-kernel - [PATCH] get_signal: simplify/cleanup the the usage of ksig->info

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Date: Fri, 23 Feb 2024 11:50:25 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>,
	Christian Brauner <brauner@...nel.org>,
	Wen Yang <wenyang.linux@...mail.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] get_signal: simplify/cleanup the the usage of ksig->info

get_signal() uses signr or ksig->info.si_signo in a chaotic way, this
looks confusing. Change it to always use signr.

This allows us to simplify the SIGNAL_GROUP_EXIT/group_exec_task branch,
it no longer needs to touch ksig at all.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/signal.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index c9c57d053ce4..690982e6595e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2727,12 +2727,15 @@ bool get_signal(struct ksignal *ksig)
 		/* Has this task already been marked for death? */
 		if ((signal->flags & SIGNAL_GROUP_EXIT) ||
 		     signal->group_exec_task) {
-			clear_siginfo(&ksig->info);
-			ksig->info.si_signo = signr = SIGKILL;
+			signr = SIGKILL;
 			sigdelset(&current->pending.signal, SIGKILL);
 			trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
-				&sighand->action[SIGKILL - 1]);
+					     &sighand->action[SIGKILL - 1]);
 			recalc_sigpending();
+			/*
+			 * implies do_group_exit(), no need to initialize
+			 * ksig->info
+			 */
 			goto fatal;
 		}
 
@@ -2842,7 +2845,7 @@ bool get_signal(struct ksignal *ksig)
 				spin_lock_irq(&sighand->siglock);
 			}
 
-			if (likely(do_signal_stop(ksig->info.si_signo))) {
+			if (likely(do_signal_stop(signr))) {
 				/* It released the siglock.  */
 				goto relock;
 			}
@@ -2866,7 +2869,7 @@ bool get_signal(struct ksignal *ksig)
 
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
-				print_fatal_signal(ksig->info.si_signo);
+				print_fatal_signal(signr);
 			proc_coredump_connector(current);
 			/*
 			 * If it was able to dump core, this kills all
@@ -2890,7 +2893,7 @@ bool get_signal(struct ksignal *ksig)
 		/*
 		 * Death signals, no core dump.
 		 */
-		do_group_exit(ksig->info.si_signo);
+		do_group_exit(signr);
 		/* NOTREACHED */
 	}
 	spin_unlock_irq(&sighand->siglock);
-- 
2.25.1.362.g51ebf55